PHP built-in functions provide the following functions: 1. Type conversion: is_numeric(), floatval(), strval(), intval(); 2. String processing: strlen(), substr(), ucwords(), strtolower(); 3. Array processing: count(), in_array(), array_merge(), array_filter(); 4. Mathematical functions: round(), pow(), sqrt(), max(); 5. Date and Time functions: time(), date(), strtotime(), mktime(). Practical example: The code snippet uses the filter_var() function to verify the validity of an email address.
Usage of PHP built-in functions
PHP built-in functions are predefined functions that can be used for various purposes without user definition. operate. They provide powerful features that simplify programming tasks and increase code reusability.
Type conversion function
is_numeric()
: Check whether the variable is a number. floatval()
: Convert the variable to a floating point number. strval()
: Convert the variable to a string. intval()
: Convert a variable to an integer. String processing function
strlen()
: Returns the length of the string. substr()
: Extract a substring from a string. ucwords()
: Capitalize the first letter of the words in the string. strtolower()
: Convert the string to lowercase. Array processing function
count()
: Returns the number of elements in the array. in_array()
: Check whether an element exists in the array. array_merge()
: Merge two or more arrays. array_filter()
: Filter elements that meet specific conditions from the array. Mathematical functions
round()
: Rounds a number to the specified number of digits. pow()
: Calculate the power of a number. sqrt()
: Calculates the square root of a number. max()
: Returns the maximum of two or more numbers. Date and time functions
time()
: Get the current timestamp. date()
: Format the timestamp into a date and time string. strtotime()
: Parses date and time strings into timestamps. mktime()
: Creates a timestamp based on the specified date and time parameters. Practical Case: Validating User Input
The following code uses a built-in function to validate the email address entered by the user:
$email = 'john@example.com'; if (!filter_var($email, FILTER_VALIDATE_EMAIL)) { echo '无效的电子邮件地址'; } else { echo '有效的电子邮件地址'; }
This code The snippet uses the filter_var()
function to verify that $email
is a valid email address and outputs the message accordingly.
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